All posts by Mike Dimmick
Below are all of Mike Dimmick's postings, with the most recent are at the bottom of the page.
Mark Barden: My belief is that the CAI-recommended levels for digital TV were set mainly to ensure that the analogue signals didn't drive amplifiers into non-linear regions, causing intermodulation. It wasn't because 60 dBuV on digital alone would cause intermod. If your signals are currently in spec, an additional 10 dB on each is unlikely to be a problem.
You are only 5 km away from Bluebell Hill and appear to have clear line-of-sight. Plugging those figures into 
Field Strength Calculator suggests that even with no aerial gain and 10m of downlead it could be over 80 dBuV on C39 (ArqA mux). I'd say that you might need attenuation - it'll depend on how much the signal is attenuated by neighbouring buildings and trees. Dave Lindsay: Digital UK's database has no way to represent 'change to antenna radiation pattern' so they list it as 'PSB Power Up'. The antenna was originally built with more beam tilt - how far the main beam is angled down from horizontal - than ultimately intended. This was to protect some transmitters in the Meridian region that used the same channels before switchover. The changes on 27 June, once those transmitters no longer need those channels, are to insert pieces of rigid feeder line to change the electrical lengths of the feed to each tier of panels, which will reduce the beam tilt and therefore increase the distance covered.
I believe the parts have to be inserted into the antenna itself. If so, it will cause some interruptions as they switch to and from the reserve antenna, possibly some complete interruptions as the workers climb past the antennas. The changes may be delayed if the weather is too severe (typically too windy) to climb the mast safely.
People in the far south of Sandy Heath's coverage area may notice a small improvement. Anyone to the north, west or east of the transmitter should ignore this; it won't have any effect on their reception. 
Mr Edwards: This is a SELF HELP website with volunteers who put their own time in to help people. The broadcasters do not routinely monitor this website (as far as we know). If you are currently having a problem and you think it's down to transmission (though usually it isn't), contact the broadcasters. There's a list of contact numbers etc at 
Broadcaster complaints details | ukfree.tv - independent free digital TV advice .
The BBC track fault reports, but mostly they and the other broadcasters rely on telemetry from the transmitters. If the fault occurs anywhere before the transmitting antenna, on a major station, they know about it and, if it affects the BBC, it should be recorded at BBC - Reception problems . This site scrapes that BBC site periodically and puts the result here as a 'Transmitter Engineering' post.
Signal levels do vary with weather conditions - just as you get red skies with dust in the atmosphere and 'heat haze', limited visibility due to fog and rain, and indeed even mirages. These are all changes to the way electromagnetic waves travel - radio and TV have much longer wavelengths than light but many of the principles are the same. Digital UK's predictor takes account of the expected variation and still reckons that better than 90% of locations in your grid square should have reliable reception for more than 99% of the time (for some services, the prediction is ALL locations in the square). That prediction is based on a good quality high-gain aerial and a fairly short downlead (cabling).
Given that, I think it's likely that it's been raining and that water has got into your aerial system. That makes it much harder for the signals to travel down the cables (coaxial cables at high frequencies are waveguides with the signal travelling on the surface of the conductors, it's very different from power cables). The improvement is likely because it's dried out. Different frequencies are affected by different amounts - usually the highest frequencies are worst affected.
You should check that any connection boxes are mounted so that the lid is facing downward, to avoid water getting in and ensure that any water that does get in can drain out. You should also check that all cables are properly secured, so they cannot rub against roof tiles or brickwork, and check that the insulation is fully intact. Also check that the cable insulation is still flexible: the insulation is damaged by UV light and eventually becomes brittle and porous, again allowing water to get in. bernard: a group C/D aerial will not provide useful gain down on C29. You really do need to replace it with a wideband, I'm afraid.
The Midlands is very crowded with signals and it just wasn't possible to fit everything into Group C/D, particularly with half that group, C63-C68, being released (C61 and C62 are also to be released, BBC A will move to C49 some time next year, expected to be October).
Anyone who had Freeview before switchover needed a wideband already. You would have had best results on Channel 5 analogue by changing to a Group E or wideband. That was probably taken into account, along with the expected population coverage, when deciding which transmitters had to have services outside the old analogue group. Yvonne: The prediction for the postcode you've provided suggests an excellent chance of getting reliable reception from the Whitby transmitter. This will provide the PSB multiplexes only after switchover in September - see references to 'Freeview Lite' or 'Freeview Light' elsewhere on this site, or the Whitby transmitter page, to see what channels will be available.
It's very unlikely that a full service from Bilsdale will be possible at that postcode, even after switchover completes. The chances of even getting the PSBs reliably are very low indeed. Currently, Whitby only provides BBC One, BBC Two, ITV1 and Channel 4 on analogue - Freeview is only currently available from Bilsdale in your area. Jay: Access to the channels is based on the serial number of the viewing card in the box. If you ask them for a new box they'll send out a new card with it, and the subscription will be associated with that card. The recording features, including playback, will go along with that card as well.
So, if you put the new card in the old box, you should be able to play back the old recordings, but you wouldn't be able to record on the new box. You probably want to keep the new card with the new box, and put that wherever you intend to watch the pay channels.
To get all features on all boxes, you need a multiroom subscription. Sky probably still have the serial number of the old card on record and could probably reactivate it; if not, they'll send out a new card for the old box.
I'm not sure if Sky's offers would extend to adding a second set of cables to the dish. Their help page on multiroom setup says:
"A “standard installation” assumes that no additional cabling, bracketry or other equipment is required or any works which are beyond the scope usual in a normal installation. A ‘standard’ installation further assumes that if you already have satellite equipment, you will not continue to use it and your existing cabling will be used in the connection of the Digital Satellite Equipment. If the installation of your Digital Satellite Equipment is not standard you will be charged a reasonable sum for any additional equipment or works that are required.
"We will advise you about these charges before we install the Digital Satellite Equipment, which may need to be re-arranged for another time. If you already have satellite equipment and you wish to continue using it and/or have it relocated within your home, you must tell us at least 24 hours prior to the installation, and in that case a separate installation charge may be payable by you. If so, we will advise you of the amount of this charge, which must be paid before the day of installation of your Digital Satellite Equipment."
Source: 
Sky TV | What equipment do I need with Sky Multiroom ? , under "I already have satellite equipment in my home, can I link it to my Sky box with Multiroom?" Jean Moore: If you stop subscribing to Sky, the box simply becomes a 'Freesat-from-Sky' receiver. See the "Compare TV" section at Compare Freeview and Freesat TV | ukfree.tv - independent free digital TV advice to see what's available on that service, and how it differs from the BBC/ITV Freesat service and from what's available through an aerial.
If you have a Sky+ box, be aware that Sky will disable the recording and time-shifting ('pause live TV') features. Also, you lose access to any previously-recorded programmes.
If you want to get recording and time-shifting features back without a subscription, you can buy a Freesat+ recorder, which just plugs in in place of your current Sky box. Steve: Signals from plain dipoles are diffused in a ring-doughnut shape. With more tiers of panels connected in-phase with each other, you get more gain in one plane and a number of additional smaller lobes. There are some angles that would indeed get no or nearly-no signal, referred to as nulls. The antenna designer therefore adds small differences in the lengths of the connections to each panel, which has the effect of reducing the nulls, at the cost of some efficiency. This is called 'null filling'.
Also, the main lobe of the transmitted signal would normally be exactly horizontal, which - due to the curve of the earth - actually misses the ground completely. Again, the changes to the relative phases allow this to be adjusted down a bit so that the peak signal lands at a reasonable point just short of the horizon - this is called 'beam tilt'.
Both null-filling and beam-tilt adjustment are performed to ensure that even those living very close will get sufficient signal. It will be less than the full 200kW, but people living this close do not need anything like that amount of power.
We don't have the design for the current transmitting aerial, but the BBC report for the old analogue aerial, with graphs showing its performance, is available at 
http://downloads.bbc.co.u….pdf . The vertical radiation patterns are on p13-p15 (figures 10-12). One-tenth or one-twentieth of the field strength is still very high indeed, there are many local relays intended to serve areas 1-2km away from the mast that have less than 100W. There are transmitters with less than 2W output, indeed there are some 'Link' sites with less than 1W, although these are really to get the signal to another relay . People that close to CP are more likely to have too much signal than too little.
As for the leaves: I believe they're more effective at blocking radio signals at UHF than your walls are, because they're mainly water (even worse when wet leaves). They also move in and out of the path when the wind blows, making for a lot of additional variation. Andre: The most likely fix is to get an even bigger dish. The free UK channels are deliberately broadcast from a satellite aerial whose footprint covers the British Isles only. Any coverage of Cyprus is accidental 'overspill', it's not intended by the broadcasters. They claim they'd have to pay much more for broadcast rights if anyone in Europe could (easily) receive it.
The ongoing digital switchover process only affects terrestrial transmission, it doesn't do anything to satellite broadcasts. The 1N satellite was introduced because the previous 2D satellite was getting old - running out of fuel to maintain its position - and had limited capacity. They took the opportunity to get a tighter beam in some areas, possible with the newer technology.
Astra 1N isn't actually designed to serve its full life at this position, and the new transmitting dish was probably designed for a different purpose. When the true replacement, 2F, goes up later this year, it may have an even tighter footprint. J Penhale:
1. No, the recording capability goes along with the viewing card, and the free card is not part of the subscription.
2. You should be able to use the existing card with the new box.
3. No, the new box would plug straight in.
To be honest, I doubt Sky would actually sell you a box to use in France. I'd just go with a Freesat+HD box, rather than a Sky box. Some channel numbers are different between the Sky and Freesat services, but otherwise there are only a tiny number of differences in the channel line-up. See Compare TV | ukfree.tv - independent free digital TV advice for the differences. You would need a Sky box if you wanted to later upgrade to a subscription for that box (perhaps get a multiroom subscription in the UK, then take the box abroad!) Liz English: No, Bluebell Hill's output is the maximum that is permitted. The frequency plan is very complex, with the same frequencies being used repeatedly all over the country, and increasing power at one site would cause problems at the other sites using the same frequencies.
The majority of equipment seems to just use the first version of the channels that it finds, not the strongest or best quality. They may tune in Crystal Palace even if Bluebell Hill provides a better signal. See Digital Region Overlap for ideas on how to solve this problem.
Newer equipment should offer you a choice of which region to store at the preferred channel numbers if it picks up more than one region. It's supposed to be part of the Freeview HD spec, but I know of some HD boxes that still get it wrong. Josh: Should be equivalent to how well they could receive analogue yesterday. The high-power digital services use the main transmitting antennas that analogue formerly used.
There has been a wide-ranging programme of antenna replacement - the main antennas have been replaced at nearly all main transmitter sites, only Sudbury's dates from before 2000 as far as I'm aware. This has been done to improve the coverage possible from each antenna but also because the previous antennas were approaching end of service life. A few had been replaced less than 10 years before DSO. Most were serviceable for digital, but at least one was replaced again (Tacolneston, for example, got a new taller mast for DSO, with a new aerial on top of it).
Dover's new main antenna is on a pentagonal form - five faces pointing in different directions - but it only has panels fitted on three of the faces, the ones pointing north-east, north-west, and south-west. There are no panels firing toward France or Belgium. You can see this being lifted into place at mb21 - The Transmission Gallery . This new antenna should send far less power into France, and we've already had reports, at the time the new antenna was fitted, that this is the case. phil: Your TV may be old enough that it can't handle the 8K mode that is used after switchover. Check the list at 
http://www.digitaluk.co.u…ment . This list isn't necessarily complete, there may be other affected equipment that isn't on that list.
Do make sure that you're doing a full retune from scratch - some equipment will ignore channels that it thinks it already knows about, or put them somewhere else in the channel list. See 
TV Re-tune for guides. If you can't find a guide for your TV, look for the 'factory reset', 'first time installation', 'default setting', or 'virgin mode' option. It may be under a System or Software Update menu rather than the tuning menu.
If after doing that you still have the channels in the wrong place in the list, your TV probably can't handle the larger Network Information Table now required to describe all the services. See http://www.digitaluk.co.u…tnit for a list of equipment known to be affected.
If your TV is on either of those lists, and the manufacturer won't help you, you'll have to buy a Freeview box to convert it. I'd recommend buying a Freeview HD box now even if you don't have an HD TV, because new services are likely to use the same system as Freeview HD, and there may be a reorganization of the existing services within the next five to ten years that also requires it. David: Sky offer a 'free' service (this is a hook to try to get you to subscribe or re-subscribe!) There are a few differences in the channel lists between Sky's free service and the BBC/ITV Freesat service. A 'free' Sky box still shows all the channels in the subscription service in the guide, you just can't watch them, while a Freesat box shows only the channels you can watch. You can compare the channels available at Compare TV | ukfree.tv - independent free digital TV advice .
Sky do disable the recording and time-shifting features of any Sky+ boxes you have. If you want those features without paying a subscription, you'd have to get a Freesat+ box. You also lose access to any previously-recorded programmes. Kevin Watkins: When retuned, some equipment seems to store some of the channels in temporary memory rather than in persistent storage. Do a 'first time installation', 'factory reset' or 'default setting' to ensure all existing channel information is fully cleared out, before retuning. This option may be on a 'Software Update' or 'Service' menu rather than on the tuning menu.
See TV Re-tune for guides on how to retune specific equipment. 5USAMonday 18 June 2012 3:06PM
John D: The multiplex carrying these channels is temporarily on low power, until 27 June. (It's actually higher than it was before switchover started, but only 10% of the power level of the other channels.) That's because it hasn't yet moved to its final frequency. I'd expect the problem to be fixed when it moves to C42 on the 27th.
These problems usually occur when a receiver is desensitised by a strong signal on an adjacent channel. If you have a booster or other amplifier, try removing it. If not, or if that doesn't help, consider adding an attenuator.DaveTuesday 19 June 2012 3:10PM
Nick, Mark Fletcher: No, it's up to UKTV to decide to forego Sky's subscription payments and broadcast free-to-air instead, relying only on ad revenue. Dave isn't available on Sky's free service either - it's encrypted and requires a subscription.
After going free-to-air, Dave could then join Freesat's service. It reportedly costs £30,000 a year to be listed in Freesat's EPG: 
JML fails in Freesat EPG listing appeal - Tech News - Digital Spy . This would be on top of Sky's charges to appear in *their* EPG. (Sky charge £21,000 per channel, but there's also a Platform Contribution Charge based on viewing figures: Dave is charged £520,910 at present though prices are changing in July).
UKTV may review their position as their contracts with Sky come up for renewal, and as Freesat grows.
Free-to-air channels are still viewable from Sky and Freesat boxes even if the channel provider doesn't pay to have them appear in the EPGs, but you have to go to Other Channels and tune them in manually. For the majority of people, that means they're invisible. 301Tuesday 19 June 2012 4:34PM
fab: Channels can offer as many audio soundtracks as they want. Usually there are two: the regular soundtrack and audio description. TVs that understand audio description properly won't show the audio description as a separate soundtrack, as it's supposed to be mixed in with the regular soundtrack to help people with sight problems understand what's going on.
The soundtracks are otherwise labelled with the language that the soundtrack is in. The code comes from ISO 639-2. This might be 'eng' for English or, for BBC Alba, 'gla' for Gaelic. 'und' means 'undetermined', which is appropriate for crowd noise only!
I suspect the reason for the 'und' stream could be so that the service can ask the TV to add the specific commentary on top of the crowd noise, and save some bandwidth. The BBC still try to remain compatible with some equipment that doesn't support MHEG interactive content, so they don't apply this to 'proper' channels, only to 301, which is normally accessed through the 'Red Button' MHEG program.
Do be careful selecting this, as some equipment remembers your last language choice - either for that channel or for all channels! KAREN SMITH: Make sure you do a full reset, deleting all the existing channel information. Many boxes/TVs have two stores for channels, a temporary one and a permanent one, with the temporary store cleared when you turn the power off. If scanned for channels, some of them don't overwrite channels they already have in the permanent store, putting them only in the temporary store. You may have one of these.
To do a full reset, look for an option called something like 'First Time Installation', 'Full Retune', 'Factory Reset', 'Default Setting', or 'Virgin Mode'. It may be on a System or Software Update menu rather than on the tuning menu. Some manufacturers have provided specific information for the model at TV Re-tune .
If it still doesn't store the channels properly, it may have a limited amount of permanent channel memory. In this case, do the full reset with the aerial unplugged. When it completes the scan, do a manual retune and tune in C46 first, then C24, C27, C42 and C39. You can ignore C45 as it only carries duplicates of some BBC services, and Sky Sports 1 and 2 which are only viewable on BT Vision or Top-Up TV equipment with a suitable viewing card.
Next Wednesday, you should repeat the same process. Sue: No problems are reported for the Thetford or Tacolneston transmitters. (See the BBC Reception Test link next to your post.) My best guess is that the power to the distribution amplifier in your building has failed. Check with other residents to see if they're having problems.
In either case, contact your landlord or agent. See 
PARAS - Professional Aerial Riggers Against The Sharks for thoughts on who to talk to.
You could also talk to them about getting the aerial changed to receive from Tacolneston instead of Thetford, though they may want to charge for this and all the users would have to agree to it: all users will have to retune after it's done. Zoe: See Compare TV | ukfree.tv - independent free digital TV advice for a comparison of the channels available on Sky's free service and the Freesat-branded service.
To watch HD channels you need an HD receiver as well as an HD TV. BBC One, BBC HD, ITV1 HD and 4hd are free-to-air on Sky and Freesat. Channel 5 HD is still encrypted but the free/expired viewing card is sufficient. Sky's HD fee is for viewing the subscription channels in HD.
If you don't already have an HD receiver it may be cheaper to get a Freesat box than to pay Sky for an upgrade (you have to sign up for 12 months HD pack to get the free box, or the standalone free offer is £175).
If you're not that bothered about HD you can still connect your existing Sky box to the new TV, assuming it still has some SCART inputs. Manufacturers have started reducing the number of SCART connections as they take up a lot of space compared to the HDMI connectors, you may find that new models only have one SCART input. Ross: The proposal on the table at an international level is to make broadcasting and mobile data 'co-primary' from 2015. That would mean countries would be allowed to launch mobile phone services in 700-800MHz as long as they co-ordinated it with each other and with broadcasting.
Ofcom's starting position does seem to be to reduce the broadcasting spectrum still further. Their consultation 
Ofcom | Securing long term benefits from scarce spectrum resources - A strategy for UHF bands IV and V has recently closed, but they haven't published any responses yet.
Co-primary does pose a problem because TV multiplexes use 8 MHz bandwidth, while LTE uses multiples of 1.4, 3, 5, 10, 15 or 20 MHz, ideally 20 MHz for maximum speeds. Within the band defined - it probably would be a new band as the US-defined bands are weird and have gaps! - the spacing between downlink and uplink channels is supposed to be fixed. (The US bands can only support 5 or 10 MHz because of this.) That would probably make fitting LTE in around TV transmissions effectively impossible.
The specifications do allow for Time-Division Duplexing, where signals from phone to tower use the same frequency as from tower to phone, rather than Frequency-Division Duplexing, where the phone-to-tower transmissions are on different frequencies from tower-to-phone. At present, though, the TDD bands are all above 1800MHz, and there aren't many deployments. All existing UK phone networks use FDD. Gerard Hunt: There are two possibilities. Either there is stale information stored in the TV's permanent channel memory, and it's not overwriting this when you retune, or it just doesn't have enough permanent memory for all the channels.
Do a 'first time installation'/'factory reset' (can also be called full reset, full retune, default setting, virgin mode, and it might be on the software update or settings menu rather than the tuning menu) to clear out the entire channel list and retune from scratch.
If you still have the problem, it's probably the second situation. For TVs with limited memory, one approach is to manually tune the multiplex with the most unwanted services, then delete the services you don't want. Repeat with the next largest multiplex, and so on.
There are specific guides for (at least some) Philips equipment at TV Re-tune productmanuals Nick: For the BBC, it is the list of UK Public Services defined in the BBC's Agreement 
BBC - BBC Trust - Charter and Agreement , with any changes made by the BBC Trust since that was last revised. Basically, anything with 'BBC' in the name, plus CBeebies. On top of that you have the Qualifying Services: ITV1/STV/UTV, Channel 4/S4C, Channel 5, and the public service teletext provider (position vacant). That's it.
The +1 services are not counted as Qualifying Services, they are licensed as general TV services. Kev Mitchell: There will be a fifth slot available on the BBC B multiplex after the Olympics have finished (while the Olympics are on, this will be 301 HD, the HD version of the first additional Olympics video stream - there is already a placeholder on channel number 304). There are suggestions that Channel 4 might have leased the space to run some E4 HD/Film4 HD service, as C4 changed the names of the service licences fairly recently to mention '(HD)'. Nothing has been published, though.
After that, additional capacity can only come from launching new multiplexes, or converting existing ones to higher-capacity modes. New multiplexes are now unlikely until 2015 or later, because Ofcom are looking into releasing C49-C60 for mobile phone/broadband, following a decision at the last World Radiocommunications Congress to put that on the agenda for the next WRC. There's space available, and costs and template contracts had been drawn up, but releasing those frequencies means that the space available for new multiplexes would most likely have to be used for existing services instead.
Converting existing multiplexes is also fairly unlikely in the short term, as the existing services would then become unavailable to anyone without a Freeview HD box. It will depend on how quickly people take up Freeview HD, or another TV service that carries the same channels.
It's technically possible to put an HD channel on an unconverted multiplex, but it would occupy about one-third of the capacity, meaning four SD channels would have to close (at least - four slots would have to be freed up, and many slots are time-shared for different parts of the day) so it's pretty unlikely to happen. igb2100: If they work now they will work after they move. If you don't have them now they won't work then either. It's down to whether your TV implements MHEG-IC correctly (or at all), receiving the multiplexes that carry the small MHEG-IC programs, and on having the TV connected to the Internet.
The way this works is that the multiplex contains Service Information mapping the logical channel number to a Service ID. In turn that Service ID points to a data stream, and that data stream broadcasts the MHEG program. If the box or TV is recognized as implementing MHEG-IC, and is one that is supported by the provider (information about the device and the MHEG interpreter is available to the MHEG program), the program uses the MHEG-IC interface to redirect the TV to the Internet stream. If it doesn't, it uses the existing MHEG features to show the 'not supported' text and a logo. These features have been used for 10 years or more to generate placeholders (using very little bitrate) for channels that are currently off-air - e.g. 81 BBC Parliament during the Olympics, or 71 CBeebies from 7pm to 6am - or are simply data services like 105 Red Button.
Because they appear as regular channels, the Electronic Programme Guide can be filled-in using Service Information data.
Because of the way this works, if you can't get the multiplex(es) that carry the Service Information, you can't view the service. At the moment, the CONNECT services (113-115) are on SDN, 110-112 and 116 are on ArqB, and The Space is on BBC B. For transmitters yet to switch over, each service is on the pre-DSO version of that mux (A, D and B respectively). Also, you will have to rescan the TV to get them to appear at all, as with any other service.
YouView will also be offering 'pure' IPTV services in their programme guide, the information about which will be downloaded by the box over the Internet, with nothing transmitted over Freeview. It remains to be seen whether any of the channels carried on commercial multiplexes decide to make live streaming available to YouView boxes and have their channels added to the YouView EPG, and whether it's possible for them to replace the non-functioning broadcast slots - their channel numbers on full-Freeview transmitters - if the receiver is missing one or more of the multiplexes (e.g. if using a Freeview Lite, PSB-only transmitter). Nedbod: The BBC A and ArqA multiplexes will move from their current channels, C62 and C61 respectively, to C50 and C49, some time in April 2013 (current plan, no specific date given). D3&4 will remain on C59 so *could* be affected by interference from 4G transmissions.
Whether your TV reception will be affected will depend on where the 4G base stations are located compared to your line-of-sight to Winter Hill, and the exact frequencies that each one uses. A 30 MHz band has been allocated for downlink (transmissions from base station to phone), from 791 to 821 MHz, in probably 5 MHz chunks (values of 10, 15 and 20 MHz are also supported, with more bandwidth providing higher bitrates, but the higher bandwidths - hence fewer channels - would means fewer cells could be fit in before having to repeat). The risk is of introducing intermodulation through too-high signals overall, though it has also been found that receivers (set-top boxes and TVs) tend to suffer poorer sensitivity when there is a loud transmission in an adjacent channel.
If a filter is required, C59 will require a shallower roll-off than for C60, but it would still be relatively steep, many dBs of roll-off over only about 8 MHz. It's possible that some filters would cost more than some Freeview equipment, but only because the equipment is now down to under £20!
The plan is for the spectrum auction winners to provide a fund for any necessary filters, and if a practical filter is not possible for this customer, to fund an alternative means of reception. There are concerns that the fund, for which £180m has been suggested as the total sum, is not large enough. Mark A: The reason for converting BBC HD to BBC Two HD is to *save money*. They don't need to employ a separate set of channel controllers, nor need to employ separate playout and continuity announcers. It saves a fairly piffling amount of money, compared to the overall BBC budget, but it's enough for it to be worth doing.
BBC Two HD will initially be a single national service as BBC One HD currently is. Nations services, matching SD, will come later.
Expect to see more BBC Three programmes getting late-night repeats on BBC One, and more BBC Four programmes getting late-night or daytime repeats on BBC Two. Partly this makes up for the loss of the spots on BBC HD, but mostly it'll be due to reduced content spending (in real terms).
If you're looking for someone to blame, blame this Government for freezing the licence fee rather than allowing it to increase in line with inflation, and for loading a bunch of required spending on the BBC licence fee that was previously paid for from other government budgets. Bernadette: The Wharfedale WDTR160 appears to be a rebranded Tvonics box, if the help guide at http://www.ukfree.tv/retu….pdf is to be believed. You could try calling the number on that page. However, the Tvonics website indicates that the company went into administration in June.
There's a suggestion that Wharfedale-branded equipment was sold by Argos. Try contacting wherever you bought it. Or, try searching for manuals for any of the other equipment listed in that document, if you can't find the manual that came with it. JG, Kev: "SI Data" stands for "Service Information" data. This is a broad-ranging term for any information carried on the multiplex that describes how the streams of data packets make up the multiplex, the information about what frequencies are used by transmitters transmitting this multiplex, and the electronic programme guide, along with programme delivery control information (accurate recording).
You would have to contact DMOL (www.dmol.co.uk) about any changes that have been made to the format of the SI data. The most recent changes listed relate to Network Change Notification Descriptors, which advertise (to compatible boxes) the retunes required for DSO in Tyne Tees and Northern Ireland, and for the renumbering exercise that was expected to occur on 19 September.
DMOL do use the DTG Testing lab to verify that their changes work on the majority of equipment in the wild, but it's possible they don't have a 3View box. Ken Collyer: DMOL is DTT Multiplex Operators Limited. It is a joint venture between the four main multiplex operators, weighted according to their ownership: thus the BBC and Arqiva have 33% shares and D3&4 and SDN have 17.5% shares.
In turn, ITV plc owns SDN directly, while it has a 12/15ths share of a 50% share of D3&4.
DMOL is not considered a customer-facing organization. Channels can complain to DMOL, viewers cannot.
Part of the problem is that most Freeview boxes do not automatically pick up these changes. The DVB Service Information specification allows for it, but they do not implement it. Newer boxes, particularly Freeview HD equipment, does do the right thing automatically. Gary Burgham: These boxes are known to have faults relating to the Network Information Table, which often show up at switchover as the retune is required. See http://www.digitaluk.co.u…tnit for who to contact.
The change to the transmissions was first introduced in late 2009, but most boxes were not affected until they were retuned. Updates to some equipment were transmitted, but you would have had to have your box in standby overnight on the dates that the updates were transmitted - some viewers never put the box in standby, either leaving it fully powered up at all times, or unplugging overnight. bri: The BBC does not yet have the facilities to produce regional news in HD. They plan to introduce services for Scotland, Wales and Northern Ireland to cover the full range of national opt-outs. At the moment, when regional news is on BBC One, BBC One HD shows a holding caption telling you to switch to BBC One SD for regional news. I expect this will continue for England.
ITV have only licenced a few HD and +1 services, I think to reduce the costs of monitoring multiple services as well as the costs of broadcasting them all on satellite. The list of services licenced on cable and satellite is at 
Ofcom | Cable and Satellite TV Channels , which shows that the services for Yorkshire and Tyne Tees are combined for HD - that means you'll get Leeds news, since the West Yorkshire region is larger/more lucrative for local advertisers than East Yorkshire or Tyne Tees.
ITV1 HD on Freeview is licenced as a national service with regional opt-outs so we can't see exactly what services there are. I believe the Freeview services are the same as the satellite ones, though. des: Because the digital transmissions *replace* analogue ones, it is not possible to run continuous test transmissions. There may, periodically, be analogue shutdowns overnight to allow digital test transmissions.
See
Digital UK - Planned Engineering Works for notice of any engineering works. It's likely that this would be listed under Limavady rather than Strabane itself.
Note that when digital test transmissions *have* been broadcast, they are deliberately broadcast without any Service Information, meaning that receivers will not pick up any services if retuned at that time. This is to prevent those boxes which do automatically retune overnight from mistakenly deleting their current set of channels. Stuart Owens: 'Sear' or 'seer', apparently. And yes, it means 'free'. M W Hodson: S4C Clirlun was included in Channel 4's original application for HD capacity on Freeview. My best guess is that Channel 4 HD will replace S4C Clirlun.
Channel 5 have twice been allocated capacity on Freeview for an HD service, and twice failed to launch. The first time, they left some aspects of their bid unconfirmed and failed to eventually tell Ofcom what those details were. The slot reverted to the BBC, who launched BBC One HD.
The second time, they reported that they would be commercially unable to launch. The fifth slot reverted to the BBC, who this time used the space for 301HD for the Olympics; it was then given to Channel 4 for C4 PG Extra during the Paralympics. We don't yet know what service will launch permanently in this space, it being expected that the BBC can't afford to run 301HD indefinitely. Squonchy: Check the specification on your box, but MPEG-4 Part 10 AVC (aka H.264) is not required for receiving Standard Definition television in the UK (yet), so it is unlikely that SD-only Freeview equipment supports it. Freeview HD boxes must support it as it is used for HD TV, and it will be used for the Northern Ireland mini-mux, which launches in October.
MPEG-4 is made up of a number of parts, and Part 10 was the *second* video encoding specified. However, it is very unlikely that Greece will be using MPEG-4 Part 2, the first encoding, as it is barely any better than MPEG-2 Part 2, as used for SD over here. Paul: Digital UK expect you to be using the Skinningrove repeater transmitter, rather than the main Bilsdale transmitter. You don't have line-of-sight over the cliffs.
The Skinningrove transmitter will be using different, slightly higher, frequencies after switchover compared to before. If you have reception problems it may be worth swapping the aerial for a group C/D or wideband design.
Skinningrove does not yet transmit ITV1, Channel 4 or Channel 5 in digital form. They will be turned on, along with the HD services, next Wednesday. The new services are expected to be available from mid-afternoon: see Digital UK - Relay transmitter switching times for updated information on the day.
If the problem persists after switchover completes, or for reassurance that the local transmitter is working properly, contact Digital UK on the number on their website. paul: Some equipment has two sets of channel memory, permanent and temporary. When the permanent memory is full, it starts putting new channels in temporary memory, which is lost when you switch off.
Make sure you are doing a full clear-out of the channel list before starting retuning. Check TV Re-tune for instructions for your TV, or look for the 'First-Time Installation', 'Factory Reset', 'Default Setting' or 'Virgin Mode' options. This option may be in the Software Update or System menu rather than in the tuning menu.
If that doesn't help, your TV may just not have enough memory for all the channels. If you can, use the manual tuning feature to just tune in the multiplexes you want, from the best transmitter - some equipment may store two copies of some channels if they are receivable from more than one transmitter. Other people have reported success by manually tuning the multiplex with the most channels, then deleting unwanted channels from that, and repeating with the next most, and so on.
Do check that your TV is not on the list of equipment with known tuning faults: see http://www.digitaluk.co.u…tnit . If it is, use the information there to contact the manufacturer. Ronald: The transmitter at Sutton Coldfield has carried HD since 21 September 2011, and The Wrekin since 20 April 2011, covering the first postcode you gave. The second postcode falls into the Wenvoe service area, which launched at the end of March 2010.
As Dave Lindsay says, the most likely explanation is that your TV is not compatible. It must support the DVB-T2 transmission standard, not just DVB-T, and it must support the MPEG-4 AVC video encoding, not just MPEG-2. The easiest thing to look for is the Freeview HD logo. Catherine O'Malley: Chances are that the conditions were right to receive a strong enough signal to be detected, and that your equipment is one of those that stores the first version of a service it finds, rather than the best available.
The Freeview guide is being updated tomorrow lunchtime to move some channels around, to make more space for the future, and change the prominence of some channels. Yesterday is swapping with Dave, moving down to number 19. I suggest you retune again after midday. You should use the same retuning process you used at switchover - see TV Re-tune for manuals and retuning guides for selected equipment. @bored now: The BBC bid makes sense as the money for it has already been top-sliced from the licence fee. If the BBC win, they will be able to combine the management effort with their existing multiplexes, and not waste any more licence fee money than necessary Mark Fletcher: Rubbish. Unless Claude Shannon's Theory of Information is wrong - which is unlikely - the maximum bitrate achievable for the conditions that the HD multiplex currently operates in (8 MHz channel, minimum 17.8 dB signal-to-noise ratio for a random white-noise channel) would be approximately 47.27 Mbit/s. The HD multiplex currently achieves 40.21 Mbit/s. The improvement is subject to diminishing return - you need more and more processing power to handle the error-correcting codes that deliver the increased capacity. Low-density parity check (LDPC) codes already approach the Shannon limit (to 0.04 dB) with block lengths of 10 million bits - rather longer than the 64,800 bits used in DVB-T2.
The only way to increase capacity further from the same bandwidth is to adopt multiple input-multiple output (MIMO) transmission. This requires the end customer to have multiple aerials pointing at the same transmitter, and the broadcasters to install multiple transmitting aerials and transmitters. Basically, it means doubling (trebling, etc) the costs, to both transmitters and receivers, for less than double (treble) the throughput.
The compression ratios may well increase, but it's worth pointing out that it's taken 14 years for the compression ratios on Freeview to allow twice the number of channels per multiplex as at onDigital's launch - and many channels on the multiplexes that do have 12 simultaneous channels are now running in reduced resolution (544x576 rather than the proper 720x576) and that many viewers consider the compression artifacts unacceptable. MPEG-4 AVC is more efficient than MPEG-2 Visual, but HD channels still average around 8 Mbit/s compared to an SD channel's 2 Mbit/s, with five times as many pixels to handle. Call it an improved efficiency factor of 20%, which allows for the fact that the level of compression artifacts (and the acceptable level) on HD at present is low.
Ultra HD would be expected, for 4K mode, to deliver 4.27x the number of pixels compared to HD. Let's say the next-generation compressor can again deliver 20% improvement compared to AVC. You still need 3.4x as much capacity as for an HD channel. That means probably not achieving even two UHD channels per multiplex.
For a technology comparison, yes, LTE Advanced (the 4G mobile phone standard) is quoted at over 1 Gbit/s, but that is achieved through wider bandwidth, up to 100 MHz, about one-third the width of the entire Freeview broadcast spectrum; deeper MIMO, up to 8x8 (8 transmitters, 8 receivers); and that is the best possible performance for receivers very close to the transmitter. In practice users will be much further away from the cell tower and won't get anything like that performance. You're also sharing the capacity with other users. 802.11n Wi-Fi similarly gets its best capacity at far higher signal-to-noise ratios, using 40 MHz bandwidth, and using MIMO techniques. DVB-T2 gets better bitrates (bits/sec/Hz) than either if you consider the SNR available, the bandwidth available, and the fact that as currently deployed, it only uses single in-single out; it can use deeper error-correcting codes, and greater modulation depth (256QAM vs 128QAM, for example), because it is expecting fixed-position mains-powered receivers rather than battery-operated mobile devices (so can require more computation power) and doesn't have to accommodate rate-adaptation because it is broadcast, rather than trying to adapt to the best rate for the targetted mobile device. Holloway John: You need to retune. Those channels are now broadcasting on a new frequency. This change is to clear channels 61 and 62 for 4G mobile phones. Arthur Morley: There are suggestions that the true coverage is substantially wider than that footprint plot suggests. However, I wouldn't depend on that. SES have just launched the Astra 2F satellite, which is designed to operate at 28.2°E, unlike 1N whose permanent home is at 19.2°E. This carries a rather tighter UK spot beam: https://sat.ses.com/webservice/images/12494500 . Also, SES have published the footprints straight away, whereas for 1N the footprint was only published months after it went up, after a lot of testing and calibration.
They haven't said so explicitly, but my expectation is that 2F will take over from 1N some time early next year, just as 1F took services from 2D. The press release about 2F's launch says:
'It is the first of a three satellite investment programme (ASTRA 2E, 2F and 2G), that provides replacement and growth capacity for the UK and Ireland at the 28.2/28.5 degrees East neighbourhood.
'"ASTRA 2F will provide seamless replacement capacity for our UK customers like BSkyB, the BBC, ITV, Channel 4 and Channel 5, and will allow us to operate additional capacity at 28.2/28.5 degrees East on SES satellites. [...]"'
- 
News - SES.com
PICK TVThursday 11 October 2012 3:53PM
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BBC News - How the Olympic torch relay is broadcast live .
http://www.arqiva.com/cor….pdf Schedule 11 (page 100 of the PDF). 
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